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Old 07-14-2013, 01:45 PM   #1
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Default Bought a Miata that won't start - Help Troubleshoot

Hi all,

I found a good deal on a 1990 Miata that was already turboed. The problem? The car cranks but does not fire.

The previous owner says the car ran fine and then one day it just stopped.

He thinks that there was a bad ground on the MSPNP and he thinks it shorted something. He also said when you plug the MSPNP ECU in, the fuel pump continuously runs, I haven't tested it yet since I just got it.

VID_20130713_155601_zps5b5cb548.mp4 Video by HardHitter2k4 | Photobucket

The link above will take you to a video of my attempting to start the car. I connected the battery, connected the stock ECU and you see the results. I was told that the ECU needs to be grounded though, so I need to try that as well.

Any idea on where to start troubleshooting/checking?

This is what the bay looks like currently and yes I know the wastegate isn't connected.


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Old 07-14-2013, 04:36 PM   #2
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Did a little work on the car just now.

Hooked up the MSPNP and tried to start the car. As usual, turned but didn't fire. Turned the car off and could hear the fuel pump or what seemed like the injectors still firing or something under the hood. Went to the battery and unplugged it. I noticed the MSPNP was lite up so I'm pretty sure it's getting power. Don't quite know what the sound was even after I stopped trying to fire it up.

After I pulled the battery, I went to the front of the car and pulled the valve cover. I didn't need to do this, but I wanted to check the condition of the timing belt.

Here's a few observations I checked along the way:

1. When I pulled the spark plugs, they didn't seem "wet" with fuel. What exactly are they supposed to look like when they are wet? Here are pictures of the plugs after I tried to fire the motor






2. Once I pulled the timing cover off, I inspected the timing belt. Checked the flex and underside of the belt itself and it looked actually brand new. Don't think it's my timing belt that is the problem. I guess one question I did have, would it be safe to hook the battery up and crank the motor to ensure the belt is good all the way around? I could also check to make sure the valve train is well. Here is a video of everything:

VID_20130714_115130_zpsc0d57fd1.mp4 Video by HardHitter2k4 | Photobucket
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Bought a Miata that won't start - Help Troubleshoot-img_20130714_113139_zps5ab47338.jpg   Bought a Miata that won't start - Help Troubleshoot-img_20130714_113150_zps69e77dbe.jpg   Bought a Miata that won't start - Help Troubleshoot-f8f435b2-c2ff-47b3-98ae-36272352b051_zps87afbff0.jpg  
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Old 07-14-2013, 05:03 PM   #3
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Have you hooked your laptop up to the ECU yet? Connecting the the ECU and reviewing the gauges/inputs would be my first task.

But, during cranking confirm the status on all these: spark, fuel, fuel pump running.


From your video I DONT hear the fuel pump priming/running, if that's the case what I'd do is go into the diagnostics box, jump F/P and GND, try starting it again and enjoy a running car. If you ST_SIGN fuse is not removed, there's a good chance the MS is not controlling the fuel pump, or there should be a jumper in the AFM connector where the AIT sensor should also be connected to...depends on how the unit was built.

But also form you video I don't see the tach moving, which means the MS is not getting the signal from the CAS, which means you're not injecting fuel or sparking plugs. You'll need to connect to your laptop with Tuner Studio, click the Diagnostics tab, check save to file, and click start. Crank for a good 20-30seconds and then click stop. Upload the CSV file you created. Then we can see if your MS is actually reading the CAS and if not, which signal is not reading if any or both and we can go from there to fix your unit. I'd also post your MSQ and upload a regular datalog during cranking (datalogging > start logging)

One more thing, if you can't connect to the MS with your lap, disconnect the TPS connector and try starting the car and/or connecting again. The unit could have been built for a vTPS and with the factory TPS connected this will cause a short to ground and the car wont run in this manner.


I hope you got a good deal, as I can have this thing running again in about 5-10minutes.
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Old 07-14-2013, 05:54 PM   #4
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@Braineack

I took a better video to show you what I'm talking about. Previously the video was with the stock ECU.


This time, the video is with the MSPNP hooked up and the F/P and Ground connected by a wire in the diagnostics box. You will note a few things on this video as you watch:

1. The MSPNP light that I originally said comes up isn't on when I try to start the car but DID come on AFTER I turned the key to off
2. The sound of what I think is the fuel injectors still shooting happened AFTER I turned the key to off and removed the key @ the 1:00 mark which is why I ran out the car to the engine bay again. You can CLEARLY hear some type of ticking.
3. @ the 1:30 mark, you can see the MSPNP light up but only the very bottom of the first P. Maybe there is a short with the MSPNP and it is the problem?

I wasn't able to hook the MSPNP up to my laptop cause I didn't have a serial port (fail) I have to go buy a serial to USB converted on Friday when I have it off.
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Old 07-15-2013, 08:18 AM   #5
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you probably need a new CAS, but the injectors cycling like that at rest is weird; you really need to connect to the MSPNP and review the tune.
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Old 07-16-2013, 12:51 AM   #6
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Thanks Braineack

I just ordered a serial to USB converted from the site so I'm hoping it gets here by Friday.

I'd be extremely happy if it is just the CAS.

It could potentially be the fueling because I've been told when you crank the motor your injectors should be wet. The pictures I have of the injectors above are after I was trying to fire the car.

To me they all look dry except the first picture of the plug. I see a slight change in color tone.
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Old 07-16-2013, 01:48 AM   #7
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injectors or plugs?
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Old 07-16-2013, 01:54 AM   #8
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Sorry, I was thinking fuel and thought injectors. The plugs should be wet according to this post:

"Also, while plugs are removed, visually inspect them for damage, excessive buildup, oil in the plug wells, or other obvious issues. Check to see if they are wet- if not, fuel is not reaching the cylinders."
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Old 07-16-2013, 02:08 AM   #9
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that's a retarded way to check for fuel.

a non-retarded way is to actaully disconnect a fuel injector and see if its firing.

or better yet, before you do any more blind testing, actually hook up to the ms and figure out what is even in there, then if everything is alright start logging and composite logging to see if you're getting signals from the cas or the issue is something else
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Old 07-16-2013, 02:37 AM   #10
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Quote:
Originally Posted by 18psi View Post
that's a retarded way to check for fuel.

a non-retarded way is to actaully disconnect a fuel injector and see if its firing.

or better yet, before you do any more blind testing, actually hook up to the ms and figure out what is even in there, then if everything is alright start logging and composite logging to see if you're getting signals from the cas or the issue is something else
Yea I'm waiting for the serial to usb converter comes in so I can hook it up.

A think I noticed is that my CEL doesn't show up when attempting to fire

"2)Step 2: Cranks but will not fire- this scenario is a bit more complex, but manageable.
a)When the key is turned to “RUN,” does the Check Engine light come on?
i)If YES: Pull stored fault codes from ECU and refer to the article to decipher them. I would recommend doing this twice- pull the codes, clear the codes by temporarily disconnecting the battery, try to start it, and then pull the codes again. This will be particularly useful if there are a lot of old codes sitting in the computer’s memory.
ii)If NO: The ECU is not firing the Check Engine Light. This means that power is not reaching the ECU, power is not reaching the Check Engine Light or the computer is bad. "
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Old 07-16-2013, 09:06 AM   #11
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now im cross posting:

Quote:
The problem is your ECU is not injecting fuel. I know this because your tachometer is not moving when you crank, which means the coil packs are not firing, which means the MSPNP is not telling them to spark, which means it's also not firing fuel, which means it's not getting a correct signal back from your CAS.

It's possible the CAS is perfectly fine, but the tune loaded on the MSPNP is completely messed up and set up improperly to read the ECU and run the car. The way the injectors are clicking makes me think there might be something odd going on with the ECU/tune.

If you were injecting fuel and not firing spark, the injectors would be completely soaked and it would smell very strongly of fuel in your garage after only a few cranks.

If you want this solved stay here; it's an ECU issue with a possible failed CAS. If you had the stock ECU and AFM, im willing to bet the car would start and run.

The MS needs to first read the signals from the CAS, sync, then it will fire the coils and inject fuel according to the loaded tune's parameters. So if the CAS is failed, or the MS is looking for a different pattern, it will never fire the coils or injectors.
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Old 07-16-2013, 10:03 AM   #12
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Quote:
Originally Posted by Braineack View Post
now im cross posting:




If you want this solved stay here; it's an ECU issue with a possible failed CAS. If you had the stock ECU and AFM, im willing to bet the car would start and run.

The MS needs to first read the signals from the CAS, sync, then it will fire the coils and inject fuel according to the loaded tune's parameters. So if the CAS is failed, or the MS is looking for a different pattern, it will never fire the coils or injectors.
I have the stock ECU, however it didn't came with the stock AFM so I'm out of luck there in troubleshooting unless I can find someone local.

I'm going to wait until I can plug the ECU into my computer and we can go from there. I'm hoping it is as simple as the CAS.
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Old 07-16-2013, 10:14 AM   #13
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it might run, in the least catch, without the AFM--you'll just have to jump F/P and GND with a wire in the diagnostics box when doing so.

Worth a shot to rule out the CAS or not.
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Old 07-16-2013, 10:20 AM   #14
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Quote:
Originally Posted by Braineack View Post
it might run, in the least catch, without the AFM--you'll just have to jump F/P and GND with a wire in the diagnostics box when doing so.

Worth a shot to rule out the CAS or not.
I'll try the stock tonight when I get home from work. Someone told me that I need to ground the stock ECU?
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Old 07-16-2013, 10:22 AM   #15
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it's grounded when you plug it in. stop talking to this person.
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Old 07-16-2013, 10:23 AM   #16
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Quote:
Originally Posted by Braineack View Post
it's grounded when you plug it in. stop talking to this person.
Haha thanks I'll try it out tonight.
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Old 07-16-2013, 12:02 PM   #17
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So I actually got to the car before I left for work.

I plugged the stock ECU in. Had a paperclip going from GND to F/P. Turned the car to the 'On' position and I could hear the fuel pump going. Tried to start the car and still didn't start. On the dash the only lights that lit up were the 'Charge' and whatever the one is to the right of it on a 1990, I think it was the 'Brake' one. No CEL lit up at all just like when the MS was plugged in.

After the car didn't fire, I took out the key, yet still heard the FP (or so I think it is the FP) running until I disconnect the battery.
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Old 07-16-2013, 12:23 PM   #18
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Shoot me a PM if you end up needingn a new CAS. I am pretty sure I have one just chilling on my garage floor.
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Old 07-16-2013, 12:32 PM   #19
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Shoot me a PM if you end up needingn a new CAS. I am pretty sure I have one just chilling on my garage floor.
Damn, I sent a guy $20 for a 1.6L CAS. A few seconds too late on my part haha. Thank you for the offer!
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Old 07-16-2013, 01:07 PM   #20
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Quote:
Originally Posted by HardHitter View Post
So I actually got to the car before I left for work.

I plugged the stock ECU in. Had a paperclip going from GND to F/P. Turned the car to the 'On' position and I could hear the fuel pump going. Tried to start the car and still didn't start. On the dash the only lights that lit up were the 'Charge' and whatever the one is to the right of it on a 1990, I think it was the 'Brake' one. No CEL lit up at all just like when the MS was plugged in.

After the car didn't fire, I took out the key, yet still heard the FP (or so I think it is the FP) running until I disconnect the battery.
good chance the CAS really is bad then.

the F/P to GND activates the pump constantly with key ON; this was necessary without the AFM as the flapper being sucked in with vacuum is actually what keeps the fuel pump relay turned on after cranking.

There shouldn't have been power still going to it with the key out, that suggests some tom-foolery in the wiring, as the fuel pump relay is powered off the main relay, which is triggered by the ignition switch.
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